Solar hot water tanks gain energy from solar-powered energy sources in addition to conventional, auxiliary energy sources, and the tanks lose energy from water use and heat loss to the surrounding environment. Homeowners and other users of solar hot water tanks want to measure the performance and cost-savings that may be attributed to using solar power.
Conventional systems typically attempt to monitor solar hot water tanks by relying on flow meters combined with temperature sensor-pairs placed in the “solar loop” portion of a solar hot water tank. These systems use the flow rate and temperature differential to derive a measurement of solar energy put into the hot water tank. However, these systems are expensive, inaccurate, and hard-to-install. For example, these systems only provide an indirect measurement of energy input.
Therefore, there is a need for providing cost-effective, accurate, and easy-to-install thermal energy metering present a variety of challenges. Improved systems for thermal energy metering are described in U.S. Application Publication No. 2013/0173205, U.S. Provisional Application No. 61/582,642, and International Application Publication No. 2013/103702 A2, which are hereby incorporated by reference.